Liquid crystal display devices have advantages of, for example, being lightweight, thin and of low power consumption, and are used for display devices of large-sized TVs in addition to small display devices of display sections of mobile phones and the like. In color liquid crystal display devices widely used today, one pixel is formed of sub pixels corresponding to three primary colors of light, i.e., red (R), green (G) and blue (B). Typically, the color difference among red, green and blue is realized by color filters.
Recently, instead of general display devices using the three primary colors, display devices using multiple, i.e., four or more, primary colors by additive mixture of color stimuli have been proposed (see, for example, Patent Documents 1 through 3). A display device providing display by use of four or more primary colors is also referred to as a “multiple primary color display device”.
Patent Document 1 discloses a liquid crystal display device providing display with four primary colors of red, green, blue and yellow, and a liquid crystal display device providing display with five primary colors of red, green, blue, yellow and cyan. Patent Document 1 also discloses a liquid crystal display device providing display with six primary colors of red, green, blue, yellow, cyan and magenta.
When the number of primary colors is increased to more than three, the area size of each of apertures of red, green and blue sub pixels is decreased. In this case, especially red, which has a relatively high lightness, cannot be fully represented. As a result, the display quality of red may be reduced. Therefore, Patent Document 2 discloses a multiple primary color display device in which one pixel includes two red sub pixels. In the multiple primary color display device disclosed in Patent Document 2, the sum of the aperture area sizes of the red sub pixels is made larger than the aperture area size of each of the other colors, so that the display quality of red is improved.
Patent Document 3 discloses a display device of four primary colors in which the aperture area sizes of red and blue sub pixels are larger than the aperture area sizes of green and yellow sub pixels. In the display device disclosed in Patent Document 3, the aperture area size of the red sub pixel is made larger to improve the display quality of red. The aperture area size of the blue sub pixel, which has a relatively low transmittance of the color filter is also made larger. Therefore, the transmittance of the entire color filters is decreased. However, even when the amount of a blue component of a backlight, which has a relatively low light emission efficiency among color components of the backlight, is decreased, the liquid crystal display device can realize a prescribed color temperature. Therefore, white, which has a high lightness (luminance), can be efficiently realized.